Gautam Samanta

Arsenic poisoning in the Ganges delta.

We have been studying the contamination of groundwater by arsenic and the attend-ant human suffering in West Bengal, India, for a decade, and in Bangladesh for the past four years. From our analysis of thousands of samples of water and sediment, we have been able to test the course of events proposed by Nickson et al. to account for the poisoning of Bangladesh groundwater. We disagree with Nickson et al.s claim that arsenic concentrations in shallow (oxic) wells are mostly below 50 μg per litre. In our samples from Bangladesh (n=9,465), 59% of the 7,800 samples taken at known depth and containing arsenic at over arsenic 50 μg per litre were collected from depths of less than 30 m, and 67% of the 167 samples with arsenic concentrations above 1,000 μg per litre were collected from wells between 11 and 15.8 m deep.

Arsenic in ground water in six districts of West Bengal, India: the biggest arsenic calamity in the world. Part I. Arsenic species in drinking water and urine of the affected people

Arsenic in ground water has been found above the maximum permissible limit in six districts of West Bengal covering an area of 34 000 km2 with a population of 30 million. At present 37 blocks of these six districts by the side of the River Ganga are affected and about 800 000 people from 312 villages/wards are drinking arsenic contaminated water and amongst them at least 175 000 people are showing arsenical skin lesions. The source of arsenic is geological. We have analysed thousands of tube-well water samples from these six districts for four arsenic species namely, arsenite, arsenate, monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA). We could detect no MMAA or DMAA in any of these samples. In urine, DMAA and MMAA are the predominant species along with arsenite and arsenate. The techniques we used for the determination and speciation of arsenic are: (i) separation of arsenite and arsenate from water by sodium diethyldithiocarbamate in chloroform followed by FI-HGAAS; (ii) spectrophotometry using Ag–DDTC in chloroform with hexamethylenetetramine as absorbing solution; (iii) ion-exchange separation of arsenite and arsenate from water followed by FI-HGAAS; and (iv) for analysis of inorganic arsenic and its metabolites in urine, FI-HGAAS was used after separation of the species by a combined cation–anion-exchange column. Total arsenic in urine was determined by FI-HGAAS after acid decomposition. The most toxic species, arsenite, is present in ground water at about 50% of the total arsenic level, and more than 90% of the total arsenic in urine is inorganic arsenic and its metabolites.

Arsenic in ground water in six districts of West Bengal, India: the biggest arsenic calamity in the world. Part 2. Arsenic concentration in drinking water, hair, nails, urine, skin-scale and liver tissue (biopsy) of the affected people

In six districts of West Bengal arsenic has been found in ground water above the maximum permissible limit recommended by the WHO of 0.05 mg l-1. This water is used by the villagers for drinking, cooking and other household purposes. These six districts have an area of 34,000 km2 and hold a population of 30 million. Over the last five years we have surveyed only a few small areas of these six affected districts and our survey revealed that, at present, at least 800,000 people from 312 villages in 37 blocks are drinking contaminated water and more than 175,000 people are showing arsenical skin lesions that are the late stages of manifestation of arsenic toxicity. Most of the three stages of arsenic-related clinical manifestations are observed amongst the affected people. The common symptoms are conjunctivitis, melanosis, depigmentation, keratosis and hyperkeratosis; cases of gangrene and malignant neoplasms are also observed. The source of arsenic is geological. We have analysed thousands of arsenic contaminated water samples. Most of the water samples contain a mixture of arsenite and arsenate and in none of them could we detect methylarsonic or dimethylarsenic acid. We have also analysed a large number of urine, hair and nail samples, several skin-scales and some liver tissues (biopsy samples) of the people drinking the arsenic contaminated water and showing arsenical skin lesions. Flow injection hydride generation atomic absorption spectrometry (FI-HGAAS) was used for the analysis of hair, nails, urine and skin-scale after decomposition by various techniques. The liver tissues were analysed by Zeeman corrected-ETAAS using a few milligrams of the biopsy samples.

Arsenic in groundwater in six districts of West Bengal, India.

Arsenic in groundwater above the WHO maximum permissible limit of 0.05 mg l−1 has been found in six districts of West Bengal covering an area of 34 000 km2 with a population of 30 million. At present, 37 administrative blocks by the side of the River Ganga and adjoining areas are affected. Areas affected by arsenic contamination in groundwater are all located in the upper delta plain, and are mostly in the abandoned meander belt. More than 800 000 people from 312 villages/wards are drinking arsenic contaminated water and amongst them at least 175 000 people show arsenical skin lesions. Thousands of tube-well water in these six districts have been analysed for arsenic species. Hair, nails, scales, urine, liver tissue analyses show elevated concentrations of arsenic in people drinking arsenic-contaminated water for a longer period. The source of the arsenic is geological. Bore-hole sediment analyses show high arsenic concentrations in only few soil layers which is found to be associated with iron-pyrites. Various social problems arise due to arsenical skin lesions in these districts. Malnutrition, poor socio-economic conditions, illiteracy, food habits and intake of arsenic-contaminated water for many years have aggravated the arsenic toxicity. In all these districts, major water demands are met from groundwater and the geochemical reaction, caused by high withdrawal of water may be the cause of arsenic leaching from the source. If alternative water resources are not utilised, a good percentage of the 30 million people of these six districts may suffer from arsenic toxicity in the near future.

High performance liquid chromatography inductively coupled plasma mass spectrometry for speciation of arsenic compounds in urine

Abstract Speciation of urinary arsenic is very important to know the extent of human exposure to inorganic arsenic and also from toxicity point of view. A high performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) system for speciation of arsenite, arsenate, monomethyl arsonic acid (MMAA), dimethyl arsenic acid (DMAA) and arsenobetaine (AB) in a single run in urine samples has been developed. The method is based on anion exchange high performance liquid chromatography (HPLC) coupled on-line to inductively coupled plasma mass spectrometer (ICP-MS). Detection limits for the five arsenic species in urine samples are between 0.01 and 0.04 μg l −1 . To validate the method, Standard Reference Material, toxic metals in freeze-dried urine SRM 2670 containing both normal and elevated levels of arsenic have been analyzed for arsenic species. Our results of arsenic species in Standard Reference Material SRM 2670 have been compared with the results of seven other laboratories. The method has been applied to determine the arsenic species in urine samples of two groups of people from two arsenic-affected villages of two districts, out of the nine affected districts of West Bengal, India. These two groups were using arsenic-contaminated water a few years ago, but are now supposed to be using safe water for drinking and cooking, as safe sources have been installed. From their urine speciation, the nature of exposure of individuals to arsenic compound could be predicted. It is concluded that, even though these groups are using safe water, they cannot avoid, from time to time, arsenic contamination as many water sources of the surrounding areas are arsenic contaminated.

Groundwater Arsenic Contamination and Suffering of People in Bangladesh

Publisher Summary The total area and population of Bangladesh are 148,393 km2 and 120 million respectively. To date, 9089 water samples collected from 60 districts have been analyzed and arsenic (As) concentrations in 41 districts have been found to be above 50 μg/l. The area and population of these 41 districts are 89,186 km2 and 76.9 million respectively. This does not mean the total population in these 41 districts are drinking contaminated water and suffering from aresenicosis, but no doubt they are at risk. About 3000 each of hair and nail samples from people living in As-affected villages (including patients) have so far been analyzed and 97% of the hair samples contain aresenic above the toxic level and 95% of the nail samples contain above the normal level. Out of the 41 districts where As has been found above 50 μg/l authors have, so far, 22 districts have been surveyed for arsenicosis patients, and in 21 districts people suffering from As-induced skin lesions have been identified.

Groundwater Arsenic Contamination and Sufferings of People in West Bengal, India and Bangladesh

Groundwater is becoming the major source of drinking water around the world, especially in developing countries, to avoid microbial and chemical contamination from surface water. Another reason of wide use of groundwater is that because of its easy access and economic viability. Not only is groundwater being used for drinking, but for farmers in many developing countries like India, Bangladesh groundwater is their main source of irrigation. These countries have achieved a green revolution with the help of underground water. Earlier, India and Bangladesh could get only one crop a year, and that too was rain dependent. But now usually 3/4 crops in a year are common and the source of water for irrigation lies underground. Irrigation in West Bengal and Bangladesh using groundwater was first started around the sixties. In both these countries, there is no groundwater withdrawal regulation. As a result, groundwater exploitation goes on unchecked. In Bangladesh and West Bengal more than 95% of the Rural Water Supply Schemes (RWSS) depend on underground water. Dhaka (population abut 11 million) is the only city in the world where more than 97% of the domestic water requirement comes from underground water sources.

Calcutta Pollution: Part V. Lead and Other Heavy Metal Contamination in a Residential Area from a Factory Producing Lead-Ingots and Lead-Alloys

Within Calcutta city of area 100 sq. km there are altogether 11516 small and big factories. And in and around Calcutta there are alone 40 factories producing only lead-ingots and lead-alloys; a few hundred thousand people live in the vicinity of these factories. Most of these factories are bereft of adequate emission treatment plant and the chimney heights also are in the range of 15–25 metres only. The analytical study of soil, water, road-dust, dust on leaves, pond-sediment of the surroundings of one such factory in Kalipark, Dum Dum is presented in this paper. The results show that the surrounding area is highly contaminated not only by lead but also from very toxic elements arsenic, cadmium and mercury.